1. Field of the Invention
The present invention relates to a color separation filter which is employed in a solid-state image pickup element or an image pickup tube to enable color image pickup and a method of manufacturing the same.
2. Description of the Prior Art
An example of a conventional color separation filter is disclosed in Japanese Patent Publication Gazette No. 17375/1977. FIG. 6 is a sectional view showing the conventional color separation filter. Referring to FIG. 6, a blue color separation filter array 7b is provided in the form of stripes on a substrate 6, which is further provided with a film 8 for preventing mixture of colors to cover the blue color separation filter array 7b. Provided on the color mixture preventing film 8 is a yellow color separation filter array 9b, which is covered by a protective coat 10.
In order to form the respective color separation filter arrays 7b and 9b, materials therefor are generally prepared in desired patterns such as stripes or mosaics to be dyed in desired density by appropriate dyestuffs of, e.g., three primary colors or complementary colors.
Thus, the conventional color separation filter is formed through a step of preparing materials to be dyed in prescribed patterns, a step of applying dyestuffs to the materials by means such as dyeing to color the same and a resist printing step for preventing mixture of colors in application of the dyestuffs of different colors.
In a conventional method of manufacturing the color separation filter, it is necessary to provide materials to be dyed in desired patterns on a prescribed substrate thereby to color the same. In general, the dyed materials, which are prepared by water-soluble high polymers such as gelatin, casein, glue and polyvinyl alcohol are photosensitized by some method to obtain the desired patterns through the so-called photoengraving process. With respect to such dyed materials, however, those excellent in resolution are inferior in dyed property while those excellent in dyed property are inferior in resolution. Such a problem leads to a significant defect for improving the density of unit filters required for increasing resolution of, e.g., an image pickup element thereby to improve the quality of pictorial images reproduced on a TV screen. Further, the conventional method requires a dyeing step for coloring, which step is not well-matched with a process such as that in the the semiconductor industry requiring extreme cleanliness.